The aim of this in vitro study was to verify the effect of different dental bleaching methods regarding the achromatic enamel color change. Forty-five bovine teeth were immersed in a darkening solution and then divided into nine experimental groups with five samples in each group. The color measurement was initially taken using a digital colorimeter. The teeth were submitted to the bleaching with three bleaching gels, without any activation source (control) and with two wavelengths (660 nm diode laser and 470 nm LED). The previous analysis of the absorption spectra enabled the choice of an adequate wavelength in order to enhance its photochemical action. The second color measurement was taken after all the treatments. The data were submitted to ANOVA and Tukey parametric statistical tests (p=0,05). It was observed that: 1) there was a statistical significant difference between the activation sources; 2) there was statistical significant difference regarding the interaction among the activation sources and the bleaching gels when compared with each other. The activation methods of the bleaching agents, even promoting color changes in distinct levels, still require further studies capable of detecting a higher absorption spectrum of a product and which presents significant clinical results.